1. Field of the Invention
This invention relates to manual controls of the joystick type useful in the operation of motorized wheelchairs. The manual controls have numerous other applications, such as in the operation of video games.
2. Description of Related Art
There is a need for inexpensive yet accurate manual controls for providing direction and speed signals for motorized wheelchairs. Controls of this type are often referred to as joystick controls. Typically, they are provided with a handle that is pivotally mounted for universal rotation about a point along its axis. Sensors are provided for sensing the angle of tilt along the perpendicular axes through the point of rotation. Numerous sensing schemes have been used, such as potentiometers in contact with brushes that move corresponding to the tilt of the joystick. See U.S. Pat. Nos. 4,856,785 and 6,259,433. Another sensing scheme involves the interaction of induction coils. See U.S. Pat. Nos. 4,879,556 and 5,911,627. Hall effect and other magnetic sensors have been used for sensing the tilt. See U.S. Pat. Nos. 5,160,918; 5,831,554; and 5,831,596.
Recently, the development of miniaturized cameras has been applied to the detection of the movement of computer mouse controls over a surface. See U.S. Pat. Nos. 6,172,354 and 6,664,948 incorporated herein by reference. However, this technology has not yet been successfully applied to joystick-type controls and, in particular, controls for battery-operated joystick-controlled wheelchairs. Computer mouse controls simply need to command relative movement of the mouse pointer on the computer monitor display and do not need to provide absolute displacement from a home position.